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Remote Controls Copiers Cel l Phones
ROHM MarketingUSA
Innovat ions Embedded
White Paper
Presented by ROHM Semiconductor
Optical Sensors
Introduction
Infrared (IR) technology addresses a broad variety of
wireless applications, especially in the areas of sensing
and remote control. Today’s newest products such as
cell phones, digital cameras, and DVD players as well
as remote controls for every market segment rely on IR
sensing and control devices. ROHM Semiconductor has
been driving technology advances that have led to a
growing number of IR sensing and communication
applications for over 40 years.
About Optical Sensors
To understand infrared technology, the best starting
point is the electromagnetic spectrum. The frequency
range and wavelengths of the entire spectrum are
shown in Figure 1. The IR portion of the electromagnetic
spectrum is usually divided into three regions: the near-,
mid- and far- infrared. The wavelengths for these regions
are shown in Table 1. Infrared wavelengths range from
red to violet. The frequencies are higher than microwave
but shorter than visible light.
Focusing on near infrared devices and applications,
PhotoOptic technologies are used for optical sensing
and optical communications with numerous general
market applications, since light is less complex than RF
when implemented as the signal source. Optical sensors
are used in industrial, consumer and other applications
for sensing movement, position, proximity, ambient light,
speed, and direction.
ROHM Semiconductor Optical Sensors 1
Using Infrared Technology for Sensing and Remote Control Applications
Figure 1. Infrared signals are near the middle of the electromagnetic spectrum, above radio and well
below gamma ray.
Table 1. Wavelengths and frequencies for the IR spectrum
IR-A: 700nm–1400nm (0-7μm – 1.4μm) Near - fi ber optic, IR sensors
IR-B: 1400nm–3000 nm (1.4μm – 3μm) Mid - heat sensing
IR-C: 3000nm–1mm (3μm – 1000μm) Far - thermal imaging
Optical wireless communication uses IR data transmis-
sion for short range applications such as computer
peripherals and PDAs (personal digital assistants). For
optical communication, a modulated IR light beam
transmitted by an emitter LED is received by a silicon
photodiode. Infrared Data Association (IrDA) standards
provide the protocol for these types of communication.
Since IR does not penetrate walls, it does not interfere
with other signals in indoor environments. IR technol-
ogy is the most commonly used technique for remotely
controlling appliances.
Some general applications for IR components include:
• Office Automation (OA) equipment such as
copiers, fax machines and printers
• Vending machines
• Gaming products
• Home entertainment products
• Medical / health care equipment
• Banking terminals such as ATMs
• Testing equipment such as IC/LSI testers,
encoders and more
Types of IR Devices
To address the variety of sensing applications, prod-
ucts take advantage of several IR technologies. These
include:
• IR Emitters
• IR Receivers (sensors)
• Photointerrupters & Photo Reflectors
• Tilt Sensors
• IrDA Communication Modules, and
• Remote Control Module Receivers
A brief explanation of each shows the commonalities
and differences.
An IR Emitter is a light emitting diode (LED). Different
types of IR LEDs are specified based on their packag-
ing and special features, such as output optical power,
wavelength, and response time.
IR Receivers are also called sensors since they detect
the wavelength and spectral radiation of the light from
the IR emitter. IR receivers are specified by optic fea-
tures, packaging, special circuitry such as an ambient
light filter, wide viewing angle, and more.
A photointerrupter is a photosensor that integrates an
optical receiver and emitter in a single U-shaped pack-
age. In a transmission type photointerrupter, the light
emitting and detecting elements are placed facing each
other (Figure 2). Shape and size are two of the main dif-
ferentiating features of a photointerrupter.
light emitter
paper
light detector
case
Figure 2. A photointerrupter integrates an emitter and
receiver in a single package.
As shown in Figure 3, product characteristics are deter-
mined by the slit and gap - the width or distance from
emitter to receiver/sensor. The vertical or horizontal slit
width is the window opening for collimating, also
slitsgap
Figure 3. Photointerrupters are specified by gap and slit
dimensions as well as outputs.
called the beam width. Besides the slit and gap, addi-
tional selection criteria include the output type, such as
analog, digital, and dual-phase output signals. Typical
ROHM Semiconductor Optical Sensors 2
applications include: printers, counters, opto encoders,
directional movement detection, and more.
Photo reflectors or reflective type sensors are side-
by-side emitter-sensor (photointerrupter) devices that
detect reflected beams from a surface. Figure 4 shows
a typical photo reflector design. Key electrical charac-
teristics are: transfer gain rate, sensor collector current
vs. IR LED current, wavelength, and response switching
time. Reflective type sensors can be used in proximity
sensing applications.
light emitter
paper
light detector
case
Figure 4. Reflective type photo sensors detect light reflected by a
target object.
Tilt sensors represent a special type of sensing design
for PhotoOptics. Figure 5 shows image rotation as part
of the sensing commonly used in portable products
with displays such as cameras and cell phones.
Orientation DetectionVideo Devices(Mobile Phones,
Digital Cameras)
Simplify preview for image
correction (i.e., autofocus,
white balance adjustment)
Filming
Previewing
Figure 5. With careful design consideration, optical tilt sensors can pro-
vide four-direction detection. Source: ROHM Semiconductor.
IrDA communication modules used in local networks
have three different forms:
• IrDA-SIR (slow speed) infrared supporting data
rates up to 115Kbps
• IrDA-MIR (medium speed) infrared supporting data
rates up to 1.15Mbps
• IrDA-FIR (fast speed) infrared supporting data
rates up to 4Mbps
To address common applications such as wireless
optical communications for mobile devices, communi-
cation modules frequently are offered in surface mount
device (SMD) packages and support SIR, MIR or FIR
data rates.
Remote control module receivers operate at a variety of
carrier frequencies (typically in the 30 to 60kHz range).
Units with a dual lens provide a higher degree and
wider range of sensitivity. The small size and (typical)
surface mount design make them ideal for embedding
in numerous applications. Lead frame versions are
also offered. Units with an integrated photo IC have
improved anti-noise characteristics.
Typical applications include:
• Audio Visual devices such as audio amplifiers,
TVs, VCRs, and CD/DVD/MD players
• Multimedia equipment
• Home appliances such as air conditioners, fans,
and lighting products
• CATV set top boxes
• Toys
• Any equipment with a wireless remote control
Specific IR Applications
IR sensors have numerous applications in several mar-
ket segments. A brief summary of markets and applica-
tions includes:
Security – movement/motion detection, fire alarms/
smoke detectors
Industrial (including automotive) - measurement,
counters, motor encoders
ROHM Semiconductor Optical Sensors 3
ROHM Semiconductor Optical Sensors 4
Medical - blood/oxygen/temperature measurement
Consumer - TVs/STBs, proximity sensors, cell phones,
tilt sensors, ATMs/kiosks, and cameras
Computers - keyboards/mice
Printers - paper/media/door detection
Game and Toys – remote control modules
Using IR in Wireless Applications
As a wireless technology, IR has advantages and
disadvantages when compared to RF and industrial,
scientific, and medical (ISM) (902-928MHz) band tech-
nologies. Advantages include:
1. Higher security: beam directionality helps ensure
that data isn’t detected or leaked to nearby devic-
es as it’s transmitted
2. High noise immunity: not as susceptible to signal
interference from other devices
3. Few international regulatory constraints
4. Relatively low power requirements: ideal for lap-
tops, cell phones, and personal digital assistants
5. Simple design implementation
The disadvantages of IR technology are:
1. Line of sight: transmitters and receivers must be
almost directly aligned
2. Blocked by common materials: people, walls,
plants, and other objects can block transmission
3. Short range: performance drops off with longer
distances
4. Light and weather sensitive: direct sunlight, rain,
fog, dust, and pollution can affect transmission
5. Speed: data rate transmission is lower than
typical wired and RF transmission
Despite these disadvantages, many applications are
well-suited to IR technology. IrDA infrared communica-
tion modules feature a number of advantages, such
as: high communication speed, high level of security,
increased design freedom (compatibility for future rede-
signing of feature set), and more.
ROHM Semiconductor IR Solutions
ROHM Semiconductor offers several products to
address each type of IR device technology. A few key
products demonstrate a broad range of capabilities
with a special focus on packaging.
IR Emitters
ROHM Semiconductor IR optical sensor technology
covers infrared light emitting diodes (LEDs). Several
products are available in both surface mount (SMD)
and through-hole (THD) configurations. Breakthrough
IR wavelength emitter technology has resulted in the
development of IR emitters that operate near 850nm.
As shown in Figure 6, phototransistors have a wide
bandwidth but with a peak sensitivity at around
800nm. The 850nm level is much closer to this peak
sensitivity (compared with conventional emitters that
operate close to 950nm), resulting in higher output effi-
ciency and an energy savings of 66%.
The new SIM-040ST demonstrates an improved peak
wavelength (870nm) and high IR power output (maxi-
mum of 100mW/sr) in a 1.6 x 2.25 x 3.1mm SMD
package. The SIM-030ST with similar performance is
offered in an even thinner (0.9mm) and smaller (2.3 x
1.95mm) form factor.
Wavelength (nm)
Rela
tive
Out
put
500
0%
20%
40%
60%
80%
100%
600 700 800 900 1000 1100
LOSS
Photo Transistor (typical)
Emitter (typical)
ROHM Emitter
Figure 6. Unlike conventional IR emitters that operate near 950nm, the
850nm operation of ROHM Semiconductor’s IR wavelength
emitter technology is much closer to the wavelength of pho-
totransistors resulting in reduced energy losses.
IR Phototransistors/Sensors
ROHM Semiconductor IR phototransistors feature high
gain and high collector current in a variety of packaging
options. For example, the SCM-014TB is a top-view
molded type with lens designed for automatic mount-
ing and SMD reflow assembly, while the SML-810TB
is a molded type lens design compatible with reverse
ROHM Semiconductor Optical Sensors 5
mounting. The RPM-012PB is a high sensitivity, side-
view sensor offered in an ultra-small 2 x 3 x 2mm sur-
face mount package featuring an ambient light filter,
making it an ideal match with the SIM-012SB photo-
emitter.
Photointerrupters
ROHM Semiconductor offers photointerrupters in both
transmission and reflective type designs. Transmission
type photointerrupters such as the RPI-0128/128 are
available in an ultra-compact (2.5 x 1.6 x 1.8mm) SMD
molded package (see Figure 7). At the same time, the
sensors maintain a tight 1.2mm gap. Compared to
current photointerrupters, this new package provides
approximately a 31.4% reduction in volume and a 28%
reduction in mass.
Figure 7. RPI-0128 is smaller and lighter than its predecessors,
the RPI-0126 and RPI-0125.
Moreover, utilization of double-mold construction (a
primary mold with the lens followed by a secondary
mold, see Figure 8) and 850nm IR wavelength emitter
technology result in high sensitivity, improved signal
accuracy, and the highest collector output current in
the industry.
Emitterside
Receiverside
primary resin
secondary resin
Figure 8. Double-mold construction contributes to increased output in
the RPI-2501 and other ROHM Semiconductor optical sensors.
RPI-151 is a two-phase photointerrupter integrating
two sensors in a single package (refer to Figure 9). In
addition to increased space savings, it can detect both
the speed and direction of a motor with greater accu-
racy than conventional photo-optical solutions utilizing
two separate sensors.
Shading Disk: Clockwise
Shading Disk: Counter-clockwise
Output
TimeOutput
Time
PTr2
PTr1
PTr1
PTr2
PTr2PTr1
Conventional NEW RPI-151
Problem 1High phase shift due to variations in
mounting position
Problem 2Requires space for 2 components
No mounting variations
Saves space
+
Figure 9. RPI-151 can detect both the spin speed and spin direction of
a motor.
The RPI-2501 is a photointerrupter with an integral
receptacle housing connector assembly. The clip-
mounted package includes a MINI CT connector (1.5
mm pitch) to conveniently connect to the PC board and
other circuitry, eliminating the need for a secondary cir-
cuit board or soldering.
RPI-2501 photointerrupter
Reflective type sensors are offered in both through-
hole and SMD package types and have a focal length
(sensing reflection distance) of 3-6mm. The main differ-
entiating feature is the peak emitting wavelength - the
RPR220C1 features a wavelength of 940nm, while the
RPR-220UC30 and RPR-220PC30N are 630nm and
470nm, respectively.
Tilt Sensors
Optimized for digital camera applications, the RPI-1040
is an optical surface mount 4-way detection sensor
consisting of an IR LED and two phototransistors (see
Figure 10). The 3.1 x 3.1 x 0.8mm package - the thin-
nest in the industry - includes a novel light shield that
ensures silent operation, avoiding noise frequently
exhibited by other designs during rotation. In addition,
the tilt sensor is not susceptible to vibration or external
energy (RF, magnetic) fields. Ideal applications include
orientation/fall/shock detection and image rotation.
Phototransistor 1Infrared LED
Phototransistor 2Light Shield
Figure 10. The RPI-1040 integrates an IR LED, two phototransistors,
and a light shield into a single package.
IrDA Communication Modules
ROHM Semiconductor’s IrDA communication modules
are among the smallest in the industry. Offered for SIR,
MIR and FIR data rates, these units feature ultra-low
power consumption. Some models offer adjustable
LED current.
RPM871 IrDA communication module
For example, the RPM871 is a micro infrared mod-
ule based on the IrDA1.2 (Low Power) standard. This
SIR-compliant product can operate at distances up to
60cm and includes an infrared LED, PIN photodiode,
and LSI circuitry in an ultra-compact, 8-pin package.
In addition to low power consumption (73μA typ.), the
module features a power down function that reduces
current consumption to 0.01μA during standby.
(RXD Output)
05
1015
2025
30
10 100 1000 10000 100000
Noise Frequency [kHz]
H
S
RPM870
Inpu
t Noi
se C
apac
ity R
ange
[Vp-
p]
ROHM Semiconductor Optical Sensors 6
ROHM Semiconductor Optical Sensors 7
Remote Control Receiver Modules
ROHM Semiconductor offers remote control receiver
modules integrating two receivers in an ultra-compact
surface mount design. 3V and 5V lead frame products
are also available featuring excellent anti-noise charac-
teristics, as well as surface mount side and top view
types.
RPM5540 remote control receiver module
For example, the RPM5540 series of ultra-compact
(3 x 8 x 2mm) surface mount remote control receiver
modules is available in both top view (H12) and side
view (H14) configurations and is 1/16th the size of
conventional products. In addition, the dual-receiver
design utilizes a 40kHz carrier frequency, operates from
a 5V supply, and features a current consumption of
only 0.95mA (typ).
Conclusion
To address the increasingly broad range of IR applica-
tions, ROHM Semiconductor has established an exten-
sive portfolio of IR sensor and remote control products
that combine the latest IR technologies with unique
ultra-compact packaging.
In addition, 40 years of IR sensor support and ongoing
advancements in the fields of LEDs and sensors allow
ROHM to meet current and future customer require-
ments. The wide product lineup includes both inte-
grated as well as discrete solutions for standard and
custom applications.
NOTE: For the most current product information, contact a ROHM sales representative in your area.
ROHM assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representations that the circuits are free from patent infringement. Specifi cations subject to change without notice for the purpose of improvement.
The products listed in this catalog are designed to be used with ordinary electronic equipment or devices (such as audio visual equipment, offi ce-automation equipment, communications devices, electrical appliances and electronic toys). Should you intend to use these products with equipment or devices which require an extremely high level of reliability and the malfunction of which would directly endanger human life (such as medical instruments, transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers and other safety devices), please be sure to consult with our sales representative in advance.
© 2011 ROHM Semiconductor USA, LLC. Although every effort has been made to ensure accuracy, ROHM accepts no responsibility for errors or omissions. Specifi cations and product availability may be revised without notice. No part of this document represents an offer or contract. Industry part numbers, where specifi ed, are given as an approximate comparative guide to circuit function only. Consult ROHM prior to use of components in safety, health or life-critical systems. All trademarks acknowledged.
CNA11003_wp
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